Oil filter cartridges used in automobile engines and other internal combustion engines employ annular filter elements mounted in filter housings which are threadably mounted on the engine. These cartridges are known as xe2x80x9cspin-on filtersxe2x80x9d because they are threadably mounted and removable. Flow paths, housing size, filter media type and location and valving systems vary, but most share several housing features, including a shell and nutplate construction, joined together by a crimp joint. U.S. Pat. Nos. 6,096,199 and 5,830,349 describe filter cartridges sharing such a housing construction.
Oil filter crimps are traditionally sealed using anaerobic adhesives, heat cure adhesives (epoxies, urethanes, etc . . . ) and/or solvent based adhesives. These materials are dispensed onto one component that will form the crimp. That component is then assembled with the second component, crimped, exposed to a heat cure to accelerate the adhesive""s cure, pressure tested as a quality audit, then allowed to condition at room temperature to continue to cure if necessary. Lot sampling is then used to pressure test the assemblies with oil under pressure to confirm the quality of the oil filters.
This process has several limitations. First, the adhesives are normally high viscosity, de-aerated materials dispensed in a bead so that they will not migrate during crimping. If the adhesive is dispensed in the wrong location, or there are air bubbles in the product, leak paths can exist that will compromise the quality of the product. Also, if there is any surface contaminants that compromise adhesion or inhibit cure, the oil filters can leak. These failure modes can only be detected after assembly and are difficult to inspect for because the adhesive is confined mechanically in a difficult to assemble crimp.
The present invention, in one aspect is a process for producing a sealed crimp joint between two substrates, each substrate having a predefined crimp area utilized to form the crimp joint. The process includes the steps of:
a) applying a photocurable sealant composition to a portion of the crimp area of at least one of the substrates,
b) irradiating the photocurable sealant in place on the substrate to cure the sealant to an immobile condition, and then
c) forming a crimp joint between the two substrates utilizing the respective crimp areas thereof.
The process is suitable for forming crimp joints between housing parts of an oil filter.
The photocuring process is a more robust process that allows for quality audits before assembly and crimp. This will reduce internal failure cost (e.g. scrap and rework), external failure costs (e.g. warranty and loss of goodwill), prevention costs (e.g. troubleshooting) and auditing costs (labor for inspection). To facilitate audit inspections, a colorant, phosphorescing and/or fluorescing agent may be included in the sealant formulations.
When the sealant is fully cured before assembly, the seal produced is essentially a compression gasket seal, rather than an adhesive seal. Accordingly the sealed joints so produced are novel products and as such constitute a further aspect of the invention.